1. Field of the Invention
This invention relates to a ceramic lining for a combustion space such as the combustion chamber of an internal combustion engine or the combustion space in a rotary kiln furnace. The lining has cavities between its inner and outer wall.
2. Description of the Prior Art
Combustion space linings made of ceramic material are used both for combustion spaces and for combustion chambers of internal combustion engines. They are used to provide thermal insulation between the hot combustion space and the metal walls surrounding it. For this purpose, the linings are designed to be compact and completely cover the metal walls. A disadvantage is that a temperature gradient occurs from the combustion space toward the surface of the lining, which leads to the depositing of heavy components of the fuels used and to the precipitation of cracking products on the lining, which are then carbonized at low temperatures on the lining into layers of soot. Undesired carbon monoxide is also produced during combustion at the wall temperatures in question, which are below 600.degree. C.
Such combustion conditions occur, in particular, in combustion spaces and combustion chambers during the starting phase. The higher the thermal conductivity of the lining, the greater the danger of the formation of deposits on the ceramic linings, since in this case there is a rapid temperature equalization with the metal walls of combustion spaces and combustion chambers.
The prior art also includes ways to reduce the thermal conductivity by placing cavities in the lining (See "Motortechnische Zeitschrift" [MTZ] 47, 1986, page 495 ff.). However, this lining of the prior art made of highly refractory material takes up a considerable amount of space on account of its cavities and flux paths. To withstand the high pressures which are experienced in the combustion chamber of an internal combustion engine, structural requirements are set which are very difficult to fulfill with ceramic materials.